The European Space Agency (ESA) is leading an initiative to help preserve the Earth’s wetlands using satellite-based observation data.

Global wetlands, which sustain the most biologically diverse ecosystems around the globe, have been in decline for much of the 20^th century and through the early part of the 21st century. To help slow down this trend, 145 national signatories committed to preserving wetlands by maintaining the ecological character of wetlands in their respective countries through the signing of the Ramsar Convention on Wetlands in 1971.

To assist these efforts, ESA launched the Globwetland project, which uses satellite imagery to provide detailed wide-area views of individual wetlands and their surrounding catchment areas to show how these areas are changing over time. ESA is currently developing and demonstrating a space-based information service based on the scientific requests of local and national users across 50 sites in 21 countries.

“Our aim is to provide what the wetland managers think is useful,” Kevin Jones of Vexcel Canada, the company managing Globwetland, said in a report on the ESA Web site. “So the first phase was carrying out a detailed survey of user requirements, to know what sites should be acquired [and] in what style. We also need to ensure that products that can be employed locally are also standardized to be of use nationally and internationally.”

With the first phase complete, Globwetland is moving into the development of prototype products based on the user requirement surveys. “In turn, wetland managers are helping us with ground-truthing our products — verifying that what is shown in an image is really there,” Jones said.

Globwetland core products include base maps, land-use cover maps and change detection maps. Historical satellite images are compared with current acquisitions to determine what changes have occurred throughout the last 10 years or more. Water cycle regime monitoring maps also are being created using Envisat and Radarsat data to show flood and retreat patterns. Specialized products, such as digital elevation models and biophysical data acquired from multispectral satellite sensors, show vegetation health based on chlorophyll levels or the sediment contents of wetland water bodies and are available on request, ESA said.

One goal of the Globwetland project is to be able to identify different types of wetlands using observation data to more accurately classify the wetlands within land cover maps, ESA reported.

“Wetlands have been very difficult to identify from space,” Doug Taylor of Wetlands International, a non-governmental organization that maintains the Ramsar sites database, said in the ESA report. “Although sensors detecting water are useful, most wetlands also are associated with vegetation, so characteristic wetland surfaces may be anything from forested or floating plants to rice paddies or wet grassland. Building up a catalog of characteristic signatures for all latitudes has only just started, so the Globwetland project, by virtue of its wide geographical and temporal reach, is a very useful platform.”